Fixed #831 by fixing a typo in the test configuration.

When I encountered #831, it was because I had changed my `hostname` setting in  `lib/environments/local.js` from `localhost` to a VMWare intranet IP so I could  test the backpack from an IE8 VM. The test configuration was overriding the `host` setting instead of the `hostname` setting, which was the wrong one to override--hence the app harness was still going back to the current config when resolving absolute URLs, instead of the test one.